title: A simple nonlinear PD controller for integrating processes.
abstract: Many industrial processes are found to be integrating in nature, for which widely used Ziegler-Nichols tuned PID controllers usually fail to provide satisfactory performance due to excessive overshoot with large settling time. Although, IMC (Internal Model Control) based PID controllers are capable to reduce the overshoot, but little improvement is found in the load disturbance response. Here, we propose an auto-tuning proportional-derivative controller (APD) where a nonlinear gain updating factor α continuously adjusts the proportional and derivative gains to achieve an overall improved performance during set point change as well as load disturbance. The value of α is obtained by a simple relation based on the instantaneous values of normalized error (eN) and change of error (ΔeN) of the controlled variable. Performance of the proposed nonlinear PD controller (APD) is tested and compared with other PD and PID tuning rules for pure integrating plus delay (IPD) and first-order integrating plus delay (FOIPD) processes. Effectiveness of the proposed scheme is verified on a laboratory scale servo position control system.
authors.affiliation: Department of of Applied Physics, University of Calcutta, 92, A.P.C. Road, Calcutta 700009, West Bengal, India. Electronic address: chanchaldey@yahoo.co.in.
authors.forename: Chanchal
authors.initials: C
authors.lastname: Dey
authors.affiliation: Department of Instrumentation & Electronics Engineering, Jadavpur University, Sector III, Block LB/8, Salt-lake, Calcutta 700098, West Bengal, India. Electronic address: rkmudi@yahoo.com.
authors.forename: Rajani K
authors.initials: RK
authors.lastname: Mudi
authors.affiliation: Department of Instrumentation & Electronics Engineering, Jadavpur University, Sector III, Block LB/8, Salt-lake, Calcutta 700098, West Bengal, India. Electronic address: chalamju10@gmail.com.
authors.forename: Dharmana
authors.initials: D
authors.lastname: Simhachalam
keywords: Integrating process; Nonlinear PD control; PID control